In our copending patent application Ser. No. 640,493 filed Dec. 15, 1975 and entitled HAND TOOL FOR CLEANING FABRIC there is disclosed a hand held head structure connected by a vacuum hose to the recovery tank of a cleaning machine. This cleaning machine further includes a fluid solution dispensing tank for passing fluid to the head through a fluid line within the vacuum hose. The end of the fluid line at the machine extends through a sealed fixture outside the vacuum hose to connect to the fluid dispensing tank. The other end of the fluid line at the hand held head similarly passes through a sealed fixture from the head to a flow control valve and thence back into the head to a nozzle in a nozzle spray chamber adjacent to the suction chamber.
As described in the aforesaid pending patent application, heated fluid is passed through the fluid line and out the spray nozzle while suction is taking place to thereby work up dirt and debris in the upholstery so that the upholstery is cleaned and such debris is removed through the vacuum hose.
Successful cleaning with a hand-held tool as described above depends, to a considerable extend, on providing the cleaning solution at a high temperature when it is dispensed from the spray nozzle in the head onto the fabric. This heat is very important in working loose the dirt and other debris in the fabric itself. While the cleaning solution is maintained at a sufficient temperature for cleaning purposes in the fluid dispensing tank of the machine, by the time it travels down the fluid line within the vacuum hose to the head, a substantial cooling has taken place. In fact, there can exist a 30.degree. F. drop in the temperature of the fluid at the head as compared to the temperature of the fluid when it initially leaves the fluid dispensing tank of the machine.